The influence of transportation improvements on interregional trade in Brazil

In this study the impact of transportation improvements on Brazilian interregional commodity flows are considered. The decreasing friction of distance is measured by two variants of the gravity model. First, distance coefficients are calculated for trade among all states in 1942 and 1962. Second, distance coefficients for each state's imports are calculated separately and then related to state per capita income, for the year, 1962. Both the time-series and cross-section results indicate a significant diminution in the friction of distance in the course of Brazilian development. The degree to which trade has integrated the national economy is assessed by the convergence of agricultural prices. Not only have interregional price differentials tended to diminish, but regional price structures are becoming more similar. The interrelation of these price structures provides a method of regionalizing the Brazilian space-economy.Most of the data for this study were collected during the author's tenure as Ford Foundation Visiting Professor at Instituto de Pesquisas Economicas, Universidade de Sao Paulo, Brazil. The Milton Fund and the Department of City and Regional Planning, both of Harvard, sustained the completion of this research. Milton Campanario and Abby Rashid provided invaliable assistance in assembling the data. Jeffrey Dutton of the Harvard Laboratory for Computer Graphics provided a program for calculating distances. William McAuliffe suggested some imaginative interpretations of the factor analysis.     

Modeling isoexposure to transit users for market potential analysis

Transit operators face a difficult fiscal environment and an imperative to contribute to urban sustainability. Under these circumstances, operators must find innovative ways to make public transportation attractive to broader segments of the public, while simultaneously trying to raise revenue to reduce reliance on public subsidies. Development of commercial partnerships is seen as a promising way to achieve these goals. Previous research has examined the potential of using geodemographics to assist transit agencies in the task of identifying potential partners for developing mutually beneficial commercial agreements. In this paper we describe an approach to model isoexposure to transit users as a tool to assess market potential. The approach is based on the analysis of walking behavior of transit users, and specifically distance walked at the end of their transit trip. Spatial modeling is used to geographically project estimates of walking distance for a desired demographic profile at a specific transit facility. After expanding the estimates using sample weights, overlays of these estimates can be used to generate variations in exposure to transit travelers at different locations in space. The approach is demonstrated using the case of Metro users in Montreal, Canada. The case study demonstrates the use of isoexposure profiles as a novel approach to generate marketing intelligence. This should be of interest to transit agencies and businesses interested in developing partnerships.     

OCS development: A new law and a new beginning

Abstract

This article reviews the conflicts that led to the establishment of a special Congressional Committee on offshore oil and gas exploration, development, and production and the attempted resolution of various issues by that Committee and the Congress in the 1978 Amendments to the Outer Continental Shelf Lands Act of 1953. A short review is provided of the history of Outer Continental Shelf (OCS) development, of the conflict between the federal government and other interested entities and persons, and of the Congressional mechanism to respond to these conflicts. A more detailed analysis is provided of the most significant OCS issues. The article describes the various risks and benefits of offshore activity and the various benefits and risks of proposed changes in the law concerning such development. A review of the Congressional mechanism to assess these risks and benefits and balance them is included in a discussion of the various issues and legislated solutions. Finally, the article notes the need for continuing oversight and review of the benefits and risks and how effective the 1978 Amendments are in balancing them.     

Partial productivity measures and total factor productivity in the air transport industry: Limitations and uses

In recent years the measurement of productivity has increasingly focused on measuring total factor productivity or TFP. Additional research has investigated the reasons for differences in TFP between firms. The implicit assumption behind this work is that simpler measures of industry productivity (such as revenue ton-miles per employee) can seriously misstate both the level and growth rate of productivity. As a result, accurate analysis of productivity requires information on TFP. While this argument is not open to debate on a theoretical basis, the extent that simple measures of productivity inaccurately portray TFP has not been investigated in anything but a cursory manner. This paper investigates the relationship between typical industry measures of productivity and TFP using a data set of U.S. and non-U.S. airlines for the period 1970–1983. The paper examines both levels of productivity and growth rates. The results indicate the extent to which industry measures accurately or inaccurately reflect the more comprehensive measure of productivity (TFP). To the extent that industry measures are inaccurate, this paper investigates the possible sources of error in order to determine if slightly altered industry measures might more accurately reflect TFP.     

Travel time ratio: the key factor of spatial reach

An important aspect of reach and accessibility is the time people are willing to spend on reaching activity places. In this paper we see the issue of travel time in an alternative way. Instead of looking at travel time separated from time spent on activities, we examine the relation between travel time and stay time. We operationalize this relation with the concept “travel time ratio”. A hypothetical framework underlying these travel time ratios is displayed. We show that for similar types of activity places the value of travel time ratio are in accordance with each other. We find large differences between trips for mandatory activities and trips for discretionary activities. The results indicate the stability of the travel time ratios. Finally, some implications for future research and policy will be mentioned. This revised version was published online in June 2006 with corrections to the Cover Date.     

Analyzing time sensitivity to discomfort in the Paris subway: an interval data model approach

We analyze individual travel discomfort-time tradeoffs in the Paris subway using stated choice experiments. The survey design allows to set up in a willingness-to-pay space to estimate the distributions of elasticities of values of travel time to crowd density and time multipliers. Several formulations of a generalized travel cost function are tested. Accounting for heterogeneity in preferences, the econometric models all take the form of an ordered probit with known bounds. We derive several estimates that could be used for fine-tuning of traffic simulation systems and more general transportation policy analysis.     

Enhancing rail infra durability through freight bogie design

The extensive usage of railway infrastructure demands a high level of robustness, which can be achieved partly by considering (and managing) the track and rolling stock as one integral system with due attention to their interface. A growing number of infra managers consider, in this framework, the track-friendliness of vehicles that have access to their tracks as a key control parameter. The aim of this study is to provide further insight into potential contributions to track-friendliness, assessed in relation to track deterioration mechanisms and cost, understanding how potential benefits are best to be utilised. Six proposed freight bogie design measures are evaluated with respect to the improvement in curving behaviour, switch negotiation and related track degradation mechanisms. To this purpose a sensitivity analysis has been carried out by means of track–train simulations in the VAMPIRE® multi body simulation software. Additionally, the impact on track deterioration costs has been calculated for those track-friendly design modifications identified as most promising. Conclusions show that the standard Y25L freight bogie design displays rather a track-friendly behaviour. Tuning the primary yaw stiffness shows a high potential to further improve track-friendliness, significantly reducing track deterioration cost at narrow radius curves and switches (by, respectively, 30% and 60%). When calculating the overall deterioration cost for the travelled route, the calculation model should include a well-balanced representation of switches and narrow radius curves.     

车胎压力监测系统简述及两种实现方案

车胎压力对汽车的安全行驶至关重要,保障车胎压力正常的汽车轮胎压力监测系统(TirePressureMonitoringSystem,TPMS)受到国内外汽车工业界越来越多的重视。本文对目前常用的两种TPMS实现方案:间接监测和直接监测方法做了详细的介绍,并对两种方法的性能指标做了全面的对比。